Barrel Crowns!

[a.JR]

Hi All ,Just crowned the barrel on the biggun, at 700 rounds , i left it to long..We found a fault in 1 land but in general it was in good nick for 700 x 77 gns of VV560 powder.. There does not seem to be any rhime or reason the the wear patterns, in another gun the one that was most supprising wear wize was a 28in Maddco in 8 twist ,6mm shooting 107s most of it's life with 2208 .. at 1000 rounds this thing just flat went off ,no retuneing would restore groups but Tony recrowned it with no other changes (i think about 31.5 of 2208/cci450/Lap case) and it sprung back to drilling holes "With The Original Load"..Long story short ,I will not shoot a barrel/case below 50 gns of any powder known to man more than 800 rounds and above 50 gn absolutly no more that 500 cartridges .. My guns will be from now on ,shoot 500 ,recrown, shoot 500 ,recrown ,then hope to get some more out of it before the old girl ends up with another shinney tomato stake..If you are shooting in competitions and have more that 800 cartridges through your favourite barrel then do your self a favour and get it crowned NOW,the cost in small compared with the results..JR..Jeff Rogers

[albow]

JR

How much do you normally get docked off the end of the tube when doing the recrown?

[a.JR]

Hi Al, No real answer,all metals and cartridge combos are different.. When done properly it's easy to measure the damage ,quick estimation is 200 to 500 thou or what ever it takes(4mm just came off my Broughton 30 cal barrel) .. A certain brand of Competition barrel in AUS is well know to those that look for losing part there of on the lands ,therefore possible to cut some off and get a bit of barrel that's worse right at the worn crown .. Use a pro in this area unless your Nashy who does his own ,cause he's a legend you know..JR..Jeff Rogers...............

JR

How much do you normally get docked off the end of the tube when doing the recrown?

[ogre6br]

AJR- what sort of crowns do you have cut? 90 degree?
Recessed 90 DEg,
11 degree target

please describe you crowns?? do you use different crown for different cartridges??

thanks

later
p

[Ned Kelly]

G'Day ogre,
it doesnt matter, I've had most types and they all work with no obvious advantages over different styles. Go with whatever your gunsmith prefers as his experience usually is a good indication of what he has found to work, just so long as they are square to the bore and I prefer a deep recessed muzzle to avoid contact damage to the trued crown surface.
Cheerio Ned

[albow]

So once you have the crown re-done, if the barrel is significantly shorter (say you had to remove .500" or maybe more) do you need to fine tune your loads again?